Problem: Khan.scratchpad.disable(); Christopher sells magazine subscriptions and earns $$7$ for every new subscriber he signs up. Christopher also earns a $$30$ weekly bonus regardless of how many magazine subscriptions he sells. If Christopher wants to earn at least $$37$ this week, what is the minimum number of subscriptions he needs to sell?
Solution: To solve this, let's set up an expression to show how much money Christopher will make. Amount earned this week $=$ $ $ Subscriptions sold $\times$ Price per subscription $+$ Weekly bonus Since Christopher wants to make at least $$37$ this week, we can turn this into an inequality. Amount earned this week $\geq $37$ Subscriptions sold $\times$ Price per subscription $+$ Weekly bonus $\geq $37$ We are solving for the number of subscriptions sold, so let subscriptions sold be represented by the variable $x$ We can now plug in: $x \cdot $7 + $30 \geq $37$ $ x \cdot $7 \geq $37 - $30 $ $ x \cdot $7 \geq $7 $ $x \geq \dfrac{7}{7} = 1$ Christopher must sell at least 1 subscriptions this week.